Flow line switches or diverters of the prior art have been subject to problems of leakage of fluid into the closed branch, of not having a substantially constant diameter flow passage and of requiring complex mechanisms for assuring simultaneous operation of two switches in the same flow system. In present day oil and gas production wells, TFL (through-flow-line) tools are used for controlling various functions. Flow lines for such tools should not have sharp bends and should have a uniform passage flow area to assure proper movement of such tools in the flow line.
The use of multiple coacting switches is encountered in many systems and in most of such systems each switch may have both out lines and return lines. In such systems, it is important that the switches function substantially simultaneously and have some type of mechanical interconnections to assure such functioning which interconnections are expensive and relatively unreliable.
Examples of such prior art structures are shown in the R. I. Kunz et al U.S. Pat. No. 3,826,539, the G. E. Lewis et al U.S. Pat. No. 3,674,123, the W. Brown U.S. Pat. No. 3,545,474, the H. Allen U.S. Pat. No. 2,749,082, the M. L. Barrett, Jr. U.S. Pat. No. 3,047,020 and the G. Larsson U.S. Pat. No. 3,146,033. The J. V. Pennington U.S. Pat. No. 3,780,756 discloses a switching device for TFL tools which is actuated by the passage of a tool through the switch.
Also known are actuators utilizing an annular piston surrounding a shaft, which is keyed to the piston by helical splines, rods or other means to prevent relative rotation of the piston, as shown in the J. C. Miller U.S. Pat. No. 2,936,737.
A further summary of diverters for TFL tools is set forth in the ASME publication entitled "Diverters for T.F.L. Tools" by Andre H. Drouin and John H. Fowler (69-Pet-4) from the ASME Petroleum Mechanical Engineering Conference at Tulsa, Okla. Sept. 21-25, 1969.